Lens



H. H. STYLL.

LENS.

Patented Jan. 11, 1921.

a m m m6 w EH,@M V mV MMJEJBZ APPLICATION FILED DEC. 9, I919. 1,364,960.

UNITED STATES PATENT v OFFICE.

HARRY H. STYLL, OF SOUTHBRIDGE, MASSAGEUSETTS.

LENS.

Specification of Letters Patent.

Patented Jan. 11, 1921.

Application filed December 9, 1919. Serial No. 343,536.

invention is the provision, as an article of manufacture for commercial sale, of an unproved form of lens blank or seml-finished lens, and of an improved process for producing the semi-finished and the completed lens.

A further object of the present invent-ion resides in the provision of a novel process of forming a two-part bifocal lens which will enable me to produce a two-part bifocal lens, in which the two parts are ground to form.

a single continuous surface after being joined one to the other, butwhich are cap'av grinding at any timev proved segment protector.

ble of separation after as may be desired.

A further object of my present invention is the provision of an improved two-part lens in which the surface on which both parts are exposed may be ground or. finished by the manufacturer, and which may then be sold to the trade for finishing of the other side, in such condition thatiit'may be handled as an ordinary lens by the shop man without any liability of injuring 0r separation of the two parts of the lens during the fubsequentgrinding and finishing of the ens. A further object of the present invention is the provision of means'for protecting the segment or supplemental lens portion secured to the main blank to prevent it so sticking to} the block on which itmay be mounted for future grinding as to render it liableito be loosened or detached by the jar incident to removal of the lens from the block, while permitting of the firm supporting of the segment bearing portion of the lens, while mounted on the block, if desired.

Other objectsand advantages of my improved lens and process of constructing the same should be readilyapparent by reference to the following specification taken in connection with the accompanying drawings forming a part thereof, and it will be understood that I may make any modifications in the specific details of construction shown and described within the scope of'the appended claims without departing from or exceeding the spirit of lily-invention.

Figure I represents a plan view of one of my commercial semi-finished blanks.

Fig. II represents an edge view thereof.

Fig. III represents a sectional view of the major blank illustrating one step in my process.

Fig. segment illustrating a further step in the process.

Fig. segment united to the main blank in condition for grinding.

I Fig. VI represents a similar sectional view illustrating the grinding of the first or bifocal surface of the blank.

' Fig. VII represents a sectional view of the semi-finished blank providedwith my im- F'ig. VIII represents a sectional view showing the protected blank mounted on a block. L

Fig. IX represents a similar View illustrating an alternative step in my process.

Fig. X represents a sectional view of the finally ground lens mounted on the block.

- Fig. XI represents a view of the completely zformed lens, the blank from wluch the same was cut being indicated in dotted line.

In the drawings, in which similar characters of reference are employed to denote corresponding parts throughout the several views, the numeral 1 designates as an entirety the major portion of the lens or blank adapted to be provided during the finishing thereof with the anterior curve 2.

In the carrying out of my invention I first form, preferably in the anterior face of the blank 1, the countersink or recess 4, which is formed to desired necessary curve to exactly receive the curved face 5 of the seg- IV represents asimilan view ofthe- V represents a sectional view of the ment or button 6, which is' adapted to be art, the blank land segment or button 6 are formed from glass of different indices of refraction, the index of refraction and the curves'4 and 5 being so figured as to give the desired reading addition to the blank so that in the final lens the visual effect through the button and'countersink will have a desired increased value or addition, the curves ground on the posterior and anterior surfaces of the blank producing various desired 'foci in the finished lens, but the power through the countersink or segment always varying by a predetermined known amount from the. prescriptive value through the major portion of the lens.

In the carrying out of my invention the members 1 and 6 having been prepared as illustrated in Figs III and IV, the next step is to suitably'secure the parts together.

accomplishing this I preferably employ a "suitable heat actuated cement, warming the parts to be united and warming the cement itself to a suitable working temperature, and then quickly and firmly pressing the parts together so that the. button or segment will be securely retained in the countersink with asthin as possible a retaining film between the curves 4 and 5. The parts when unitedwill then present substantially the a pearance of the blank illustrated in Fig. l the button 6 projecting somewhat outwardly beyond the countersink, it being necessary'to suitably grind away the button during the next step in my process.

The next step in the process of manufacture of my improved bifocal is illustrated in Fig. VI. It will be noted by a comparison of Figs. V and VI that in this step the outer or anterior curve 2 is formed on the blank, in the formation of this curve a portion of the button 6 being ground away so that a continuous curve extends across the entire front face of the semi-finished blank and the line of joinder between the blank and segment on account of the simultaneous grinding of the parts and formation of the single continuous curved surface is rendered practically invisible so that the parts present the appearance of a singlecontinuous structure rather than a attempted to separately grind the button and the lens and then merely fit the button if at all, that difficulties in the manufacture of the lens, imperfections and the like, are brought out, while the opposite face of the ronounced line, as has hitherto been experienced when t was lens being a single plain piece of glass can satisfactorily be ground by the shop man and by suitable variance in the curve on the ocular side the desired prescriptive value of the lens produced.

In either event, however, it is necessary, after the bifocal side of the lens has been ground, to mount the lens on a suitable block 7, retaining it in place on the block by the use of a pitch or similar adhesive medium 8, itlld to then grind the'second surface of the In those cases where it is desired to sell and ship the blank especially and also in the regular manufacture of theblank, it is IleC-i essa'ry for the obtaining of best results, that some means be provided for protecting the segment and absolutely preventing accidental loosening of the same during the second grinding operation or duringt-he loosening of the lens from the adhesive '8 after the grinding has beencompleted. In fact it is at this point that considerable difliculty might be otherwise experienced in the formation of this type of bifocal, since while the cement connecting the major blank and segment is sufiicient to retain the segment under all ordinary conditions, on account ofthe fact that a cement has been employed which will permit of subsequent separation of the parts, if desired, the parts are not abeither by picking, that is by prying with a v sharp instrument under one edge, or by giving one or more sharp blows or raps; to the block, the jar breaking the hold between the pitch or retaining medium 8 and the lens without the liability of breakage of the lens or pulling pieces off the lens, as might occur were it attempted to simply pull off the lens. I Naturally this ar, sufficient to break the adhesion of the substance 8 to the entire body of the lens, would have a tendency to-loos'en the engagement of the segment with the main blank so that there would be a possibility of the segment being either loosened by the jar or pulledloose in case the lens were picked off on accountof the opposed adhesive action of the cement on the one side ofthe'segment and the adhesive 8 on the opposite side of the segment working to pull the segment in opposite directions. -One of; the purposes of my present invention, therefore, is the protection of the segment in such manner that the adhesive 8 will-not act thereagainst, and the consequent tendency to loosening of the segment during the sec ond grinding operation largely eliminated. In the accomplishment of-this result I preferably apply to the segment and immediately contiguous portion of the major blank, a protecting coating or covering 9,

which will serve to prevent the pitch or ad cial care being observed, it will be understood that if preferred, as in the case of large establishments having a great deal of this work to do, the block may be prepared to receive the lens in place of the lens being prepared to fit on the block, this being considered by me an equivalent alternative step in my present process.

This alternative step in my process, I have illustrated in Fig. IX, in which I have shown the pitch as indented, relieved or removed at 10, so that a recess is formed spanning the segment 9 so that there is no pitch at this point which could adhere to the segment. The only disadvantage here present is that the lens is not as thoroughly supported for the grinding of the second surface and that more care must be observed in the mounting of the lens on this type of block, although very satisfactory results may be obtained in this manner.

In both forms the general result obtained is the same, however, that the pitch orthe like is prevented from adhering to the button or segment 6, while the coating .9 also serves to an extent as a heat insulator when the lens is being mounted on the hot pitch, and prevents any possibility of loosening of the retaining cement on account of the conducted heat.

The lens having been mounted with the button protected as described, it is then merely necessary to grind the necessary prescription curve thereon, after which the lens is removed from the block, the protector 9 removed from the segment if the same has not remained adhering to the pitch, and the lens cut into final finished form. It will: be understood, however, that if preferred to thus protect the more delicate readmg portion or segment of the lens, the protecting coating may be left over the segment as indicated in Fig. XI,'until after the completed lens has been cut out, edged and if desired placed in the mounting and then the coating removed as the final step in the completion of the lens for visual purposes.

From the foregoing specification taken in connection with the accompanying drawings, the method of construction and structure of my improved semi-finished lens blankshould be readily understood, and it will be seen that I have provided an improved process by which it is possible to produce as a commercial product a two-part bifocal lens in which the major blank and segment are united one to the other by cement but in which a substantially invisible line of cinder between the two, parts is obtained. It will further be noted that by the use of my improvedprocess I am able to produce and put out blanks in semi-finished form which can be readily finished in the ordinary prescription shop without liability of damage to or detachment of the segment and which will permit the handling of the lens in the same manner as in ordinary plain meniscus or toric.

It will also be noted that my improved segment cover 9 serves as a retainer for locking the member 6 in correct position within the countersink.

As is well known in connection with the grinding of optical lenses and polishing of same, av greater or less degree of heat is gen- I,

erated and frequently the heating of the lens is sufiicient to soften the cementitious medium used in securing-the segment within the countersink. This softening is sufiicient to cause the cement to act as a lubricant rather than a retaining member so that the segment might have a sliding movement relative to the major blank. On account of the presence of my cover member, however, overlapping the segment and engaging the blank proper circumferentially of the'segment, the segment is firmly and securely held against any such accidental sliding movement.

I claim: v

- 1. As an article of manufacture, a semifinished lens blank, comprising a major portion having a countersink, a segment removably secured within the countersink, the

side and a protecting coating secured to said surface and overlying the segment and line ofjoinder between the segment and. the main blank, substantially as and for the purpose described. v

-2. The process of forming a bifocal lens, including forming a major blank with a countersink, forming a segment to fit within the countersink, securing the segment within the countersink, simultaneously grinding the blank and segment to produce a single curve, placing a protecting coating over the segment, mounting the ground lens on a block, grinding the opposite face of the lens, removing the lens from the block and subsequently removing the coating from the segment and shaping the finished lens.

3. The process of forming a two-part bifocal lens, consisting in securing a segment to one face of a major blank, simultaneously grinding the segment and face of the blank to produce a finshed surface on that side of out of engagement with the block, and the the blank, placing a protecting coating over surrounding major portion of the lens in the segment, grindingthe opposite face ofthe. engagement therewith, grinding the second 15 blank, and removing the. coating after the surface of the lens, removing the lens from 5 grinding operation has been completed. the block and cutting the finished lens from 4. The process of forming a bifocal lens, the blank thus formed. including securing a segment to one face of In testimony whereof I have aflixed my the major blank, simultaneously grinding signature, iii-presence of two witnesses. the segment and face of the blank to 'pro- HARRY H. STYLL. 10 duce a finished surface, preparing a lens Witnesses:

block to receive said surface, mounting the H. K. PARSONS, lens on the block with the segment portion Anon G. HASKELL. 

